Amphibian-derived peptide AL-VI10 reverses vascular aging via CD44-SIRT1-Nrf2 pathway activation

Vascular aging is a primary contributor to cardiovascular morbidity and mortality, driven by fundamental molecular and cellular aging pathways. Current interventions often fall short in targeting these core mechanisms, leaving a significant gap in preventing age-related vascular pathologies. Endothelial cell dysfunction and accumulation of senescent cells are key drivers, leading to increased inflammation, oxidative stress, and impaired vascular function. Investigating novel compounds like AL-VI10 that can modulate these specific aging pathways, such as SIRT1 and Nrf2, is crucial for developing effective anti-aging strategies.

Researchers investigated the anti-vascular aging activity of AL-VI10, a novel peptide from amphibian skin, in both in vivo and in vitro models. For in vivo studies, a D-galactose-induced mouse model of aging was used to assess vascular aging phenotypes. In vitro, hydrogen peroxide (H2O2)-induced senescent human umbilical vein endothelial cells (HUVECs) served as a model for cellular senescence. Primary endpoints included changes in medial thickness, inflammatory cytokine expression, MMP levels, SA-β-gal activity, p53 and p21 expression, endothelial proliferation, migration, and eNOS expression. Mechanistic studies involved pharmacological inhibition of SIRT1 and Nrf2, as well as CD44 knockdown experiments.

AL-VI10 demonstrated excellent biosafety, showing no detectable cytotoxic or hemolytic activity. It exhibited potent free radical scavenging capacity, enhanced antioxidant enzyme activity, and reduced reactive oxygen species (ROS) accumulation. In the D-galactose-induced mouse model, AL-VI10 significantly attenuated vascular aging-associated phenotypes, including increased medial thickness, elevated expression of inflammatory cytokines, and up-regulation of matrix metalloproteinase levels, while simultaneously promoting autophagy. In H2O2-induced senescent HUVECs, AL-VI10 reduced senescence-associated β-galactosidase (SA-β-gal) activity, down-regulated senescence markers p53 and p21, enhanced endothelial proliferation and migration, and increased endothelial nitric oxide synthase expression. Mechanistic analyses revealed that AL-VI10 up-regulated silent information regulator 1 (SIRT1) and nuclear factor erythroid 2-related factor 2 (Nrf2). > Pharmacological inhibition of SIRT1 suppressed AL-VI10-induced Nrf2 activation and weakened its anti-senescence effects, while inhibition of Nrf2 reversed ROS reduction and impaired endothelial recovery. Further analysis showed direct binding of AL-VI10 to the extracellular domain of CD44, and CD44 knockdown abolished activation of the SIRT1-Nrf2 axis and eliminated AL-VI10's anti-senescence activity.